Sliver opening devices in the form of opening rollers have been known for a long time in connection with open-end spinning devices. The rotatably seated opening rollers have a sawtooth card clothing which encircles a cylindrical roller body and which can be produced in accordance with diverse manufacturing processes.
For example, a sawtooth card clothing for an opening roller is known from German Patent Publication DE 35 15 153 C2, formed as a one-piece ring wherein a helically extending groove is initially cut into a bushing-like component of hardenable steel and subsequently a plurality of cuts are machined into the bushing-like component parallel with the center longitudinal axis of the component. Several rows of teeth, which are arranged next to each other and have willowing teeth, are created in this way. Thereafter the sawtooth card clothing is hardened at least in the area of the tips of the teeth.
In a further manufacturing method, a sawtooth wire is wrapped around the cylindrical roller body of the opening roller. The respective ends of the sawtooth wire are then fastened on the roller body. With these opening rollers, known for example from German Patent Publication DE 29 04 841 A1, at least the sawtooth tips are also hardened.
A similarly designed opening roller is described in German Patent Publication DE 24 33 769 A1. This known opening roller has a sawtooth card clothing made of a wire body which is preformed in the manner of a helical spring. The preformed wire body is pushed on the cylindrical roller body and fixed in place thereon.
It has been possible over the course of time to increase the service life of the saw tooth clothing by improving the steel quality and therefore to clearly increase the degree of effectiveness of the opening rollers. However, since the willowing teeth of these devices, which rotate at a relatively high speed, are subject to considerable wear, the service life which can be achieved remains capable of being improved.
An opening roller is described in German Patent Publication DE 196 01 036 A1, wherein the ring of the card clothing is a component formed as a one-piece replacement ring. According to this publication, both the card clothing ring and the replacement ring consist of a high-quality and therefore expensive ceramic material. It is particularly disadvantageous in such a design that, when the clothing set ring is worn or damaged, the entire expensive replacement must be exchanged.